I think you'll be fine, and I think you might be worried over nothing. Do not add Bone Meal---especially on top of the soil.

You may be worrying unnecessarily :-)

First, blood meal is only effective as a deterrent to critters if it remains dry - the suggestion is to place it around in small containers and replace as necessary after rains. It is almost entirely soluble and when it comes into contact with moist soil or when watered in, it will break down rapidly into its elemental forms. Some rodents (squirrels in particular) also seem to develop a taste for blood meal so its effectiveness as a deterrent is questionable. It is also likely to draw the attention of dogs, raccoons or other carnivores. Caging the bulbs would be a much better method.

There IS a risk of blood meal 'burning' plants if applied excessively or if it comes into direct contact with plant roots. And while it does carry relatively high levels of nitrogen for an organic product, it is not very long lasting and is pretty much fully dissipated in 3-4 months. Nitrogen is required for good bulb health - it is only excessive amounts that can encourage foliar production at the expense of flowers but 1/2 cup is not an overly excessive amount over a 32 square foot area. FWIW, blood meal is a typical ingredient in organic bulb fertlizers as well as an often recommended amendment for bulb planting, if used in moderation.

Whew. So you don't think that blood meal on top of the soil will hurt the really shallow bulbs (like crocus or dwarf iris)? It won't seep into the top few inches and put too much nitrogen in?

Thanks so much for all your feedback, by the way!!

Back to how to deter critters from digging up bulbs.

I've had good luck with laying sections of chicken wire flat on the ground. Plants grow through and cover the wire and racoons/skunks don't dig up plants.

As a follow up, my cooperative extension office emailed me regarding my question and agreed that the blood meal on the surface wouldn't harm the bulbs because it would have long dissipated before they bloom. He was also in agreement about the chicken wire solution for squirrels, however as I live in a town house, our HOA would not allow me to lay chicken wire across the beds (even under the mulch) and I have bushes and annuals also in the beds that would make it an impossible task for me to do effectively. I will have to stick with blood meal (around the edges!) and cayenne pepper and red pepper flakes.

As a FYI - I used what red pepper I had in the kitchen the other day and the squirrels avoided those sections of the beds. Anywhere there was NOT cayenne or red pepper flakes, however, were clearly "explored" by the squirrels. Time to head to Costco and buy the red pepper in bulk!!

If we believe that bulbs do not need fertilizing when first planted, then putting blood meal where the bulb, when it forms its roots, will take up its heavy nitrogen content, and may force it to grow in earnest too early, bringing foliage up while the ground is still in a frost state, I'd say using blood meal is not the thing to do.
Whether putting bone meal or another phosphurus adding material to the ground can help....experts say YES...helping the bulb to feed its roots is a way to improve the foliage and flower production.
But it is mixed with the soil when first planted...not sprinkled on top.

If a squirrel has the intention to dig, nothing short of removing its claws, will prevent it. The chicken wire, if its small enough, but large enough to allow the foliage to come through it, can work if the squirrel has a time to get by it. Sensing the soil there is soft from digging, the wire will move easily with the animals digging and probably only put up a barrier for a short time.
Put a preying bird ontop of the ground, he might take a look and run for cover....or he may laugh at the silliness of the planter to think he can be fooled so easy and take a bite out of it as well. A snake of the same intent will probably leave the animal guffawing and rolling on the ground in hysterics. But, what the hey, it can be tried.
They sell plastic owls in stores....but move it around, the squirrel might be fooled once.....shame on him.....
but fooled twice...shame on you for not thinking of it sooner.

Next time you plant dig the trench 2-3 inches deeper then you want the bulb. Put down a layer of very well rotten compost, then cover it with 1/2 inch of clean sand. Lay a V of chick or rabbit wire in the trench that is now the right depth for the bulb. The V-shaped wire should not be higher then the grade of the bed. Set the bulbs in the trench, fold the tips of the wire over & tie them/ hook them, so they will not come apart.NEVER put bulbs in or next to compost or they could rot.
The pest can not get your bulbs in the wire V. And at $50.00 to $100.00 a piece for some bulbs, the wire will pay for it's self.